The unusual wave-like clouds were called asperitas clouds, which in this case formed in a layer of stratocumulus cloud that was passing over Melbourne. This means the more technical name for Thursday morning's weird and wavy clouds was 'stratocumulus asperitas'. There's one to keep in mind for the next trivia night!

Asperitas clouds often look like a rough sea that's formed on the underside of a uniform cloud bank. They can happen at varying heights in the atmosphere and are thought to be caused by a combination of sinking air and contrasting wind in the atmosphere.